Thread: Merlins

As vnx205 said,it is not until you get past the hype and chest beating that you understand the real reason for alot of what happened and the way it did happen.The second world war was a very closely run thing in the early stages and if it wasn't for a few,and I don't mean the pilots it could of turned out different.If Mitchell had made the plane the RAF asked for instead of what they needed or RR didn't stay with the merlin after all it's trouble and Hooker hadn't made a two stage SC,the list goes on.Germany made alot of very good things,the mauser,FW190.Me262 but what they needed more than anything else was Me 109 drop tanks.There is no one best engine or plane,it's like comparing LR's to tojo's,each has it's fobles. Pat

Originally Posted by flagg

Interesting.. I never knew that about the P38 variant, having only really followed the P51 which (intially) only had the single stage, single speed supercharger and didn't get the altitude performance until the Merlin variant - as you mention.

The P51 with the Allison engine went into service in 1940, from memory, the P38 first saw action in 1942 and the engines Brian refers to were not in service until 1943. There was a lot of engine development in those three years!

The P38, like the Mosquito, and to a lesser extent the Beaufighter, showed that there was a real opportunity for twin engined fighter aircraft, where the higher payload allowed longer range and heavier armament - and nose mounted armament was a lot more accurate and had no convergence problem.

Unfortunately, the P38 (apparently unlike the Mosquito, but like the single engined Tempest at similar speeds) suffered from handling problems related to compressibility effects that killed several test pilots and continued in service with several losses. (The centre of lift moved aft in a high speed dive, steepening the dive, and at the same time the controls locked. The problem was little understood at the time.) Eventually the problem was 'fixed' by fitting dive flaps.

John

Here's a photo of a young lad tinkering with his Dad's engine.

The lad is Rob Eastgate, son of Bob who owns Mustang VH-BOB.

Originally Posted by JDNSW

The P51 with the Allison engine went into service in 1940, from memory, the P38 first saw action in 1942 and the engines Brian refers to were not in service until 1943. There was a lot of engine development in those three years!

The P38, like the Mosquito, and to a lesser extent the Beaufighter, showed that there was a real opportunity for twin engined fighter aircraft, where the higher payload allowed longer range and heavier armament - and nose mounted armament was a lot more accurate and had no convergence problem.

Unfortunately, the P38 (apparently unlike the Mosquito, but like the single engined Tempest at similar speeds) suffered from handling problems related to compressibility effects that killed several test pilots and continued in service with several losses. (The centre of lift moved aft in a high speed dive, steepening the dive, and at the same time the controls locked. The problem was little understood at the time.) Eventually the problem was 'fixed' by fitting dive flaps.

John

jd, all the references I can find indicate that all Lightnings were turbocharged and intercooled except the ones ordered by the RAF, only three of which were delivered and the rest taken by the USAAF and converted to their spec. The yanks then regarded their turbocharging work as top secret and wouldn't supply it to the RAF. All Lightnings had handed engines except the ones supplied to the RAF who didn't want to know about this. The difficult handling produced by two engines running the same way caused the RAF to reject the type. Engine ratings were from 1150hp in the first deliveries, July 1941, and steadily increased. The P38H had 1425 take-off hp, and 1600 full military hp. The second most numerous variant, P38J, had the same rated engines but better airscrews and intercoolers giving improved performance. The J was the first with the dive brakes. Later marks had engines up to 1800 take-off hp and 1520 hp @ 30,000 ft with over 35,000ft service ceilings. 3800 P38l's were built. The P38 had numerous variants, almost as many engine ratings, and was produced as a fighter, night fighter, fighter-bomber, bomber, pathfinder, ground attack, photo reconnaisance, trainer aircraft. Almost 10,000 P38 Lightnings were built.

This thread is better than the Discovery channel.

P38's look evil - pity they weren't that widely used in Europe.




I prefer them to the p38a model

Originally Posted by Brian Hjelm

jd, all the references I can find indicate that all Lightnings were turbocharged and intercooled except the ones ordered by the RAF, only three of which were delivered and the rest taken by the USAAF and converted to their spec. The yanks then regarded their turbocharging work as top secret and wouldn't supply it to the RAF. All Lightnings had handed engines except the ones supplied to the RAF who didn't want to know about this. The difficult handling produced by two engines running the same way caused the RAF to reject the type. Engine ratings were from 1150hp in the first deliveries, July 1941, and steadily increased. The P38H had 1425 take-off hp, and 1600 full military hp. The second most numerous variant, P38J, had the same rated engines but better airscrews and intercoolers giving improved performance. The J was the first with the dive brakes. Later marks had engines up to 1800 take-off hp and 1520 hp @ 30,000 ft with over 35,000ft service ceilings. 3800 P38l's were built. The P38 had numerous variants, almost as many engine ratings, and was produced as a fighter, night fighter, fighter-bomber, bomber, pathfinder, ground attack, photo reconnaisance, trainer aircraft. Almost 10,000 P38 Lightnings were built.

You are right about the turbochargers and intercoolers being fitted from the start, but it was not until the P38J that performance of the engines looked better than the Merlin, with better intercoolers (also less vulnerable).

The British ordered P38s with non-handed engines to retain commonality with the P40 engines, rather than rejecting the concept. After the first few were delivered they changed the order for the remaining ones to be delivered with handed engines, but most of that batch were rejected for a variety of reasons, probably mainly because of the dangerous dive characteristics, but also because with the Battle of Britain over, and production of their own aircraft ramping up, the situation was less critical. Another point is that I suspect the conservative RAAF did not like the concept of a fighter with tricycle undercarriage. Lockheed sued the RAAF, but the case was dropped after Pearl Harbour when the USAAF gratefully took the planes.

John

I have been thinking about how to tell the country of manufacture of Merlins. I am sure that most of the ones I worked on were Packards. If you have the accessory drive housing apart the difference is plain. Packards had a planetary drive of their own design. UK ones had a coupling whose proprietary name escapes me now. US engines had US magnetos, American Bosch and Scintilla, and the UK ones had various British magnetos. USA engines all had Bendix-Stromberg carbs, and UK ones had either SU or Bendix-Stromberg. If the reduction gear and propellor spline are still fitted, this can be another indicator as Packard used two spline patterns, American or British as required. The UK engines had only the British pattern.

R-R historian Pugh records that Packard signed the agreement on 3/9/40 and had two engines running on test beds on 2/8/41 despite delays caused by the decision to continue to use British threads and the time taken to manufacture the necessary tooling in the US. British industry was already over-stretched and could not supply. In 1944 Packard produced just short of 24,000 Merlins and Pugh notes Packard's total production was 55,500.

GM's historians record that the Allison Division was engaged in producing aircraft engines, aircraft engine bearings, and "reaction propulsion power units". Other GM divisions supplying Allison are noted as Cadillac, Chevrolet, Delco-Remy, New Departure, Hyatt Bearing, Delco Products, Packard Electric, AC Spark Plug, Antioch Foundry, Harrison Radiator, & Inland, with numbers of outside firms supplying raw materials, and semi-finished and fully finished parts.

Buick converted to making Pratt & Whitney engines and commenced in early 1942. They achieved the 1942 target in the first 6 months and by the end of 1944 had produced over 62,000 engines.

Chevrolet were making three models of Pratt & Whitney engine involving seventeen of their plants. Their aircraft work also included aluminium forgings for airscrew blades and hubs, pistons, landing gear, crankcase sections. Chev. also made numerous small steel parts for aircraft and converted a large part of their major grey iron foundry to producing magnesium castings.

You really have to visit there to understand the sheer scale and capacity of US industry.

Keep it up you two. Pat